Tubing clamps are ubiquitous in the medical industry and tens of thousands are used each day in myriad applications such as flow control for IV bags, blood donor bags and even sealing the umbilical cord of a newborn. Varying sizes and types of tubing clamps may be used for different applications.
One of the most prevalent medical tubing clamps is the Halkey-Roberts type clamp. This clamp is effective for controlling blood flow to donation bags, for controlling or shutting-off flow in IV bags and for controlling dosage of intravenous drugs. The Halkey-Roberts type clamp has a laminar body, bent back onto itself in essentially a u-shape with, two apertures allowing the flexible tubing to be passed longitudinally through the clamp body and over two opposing cleats or bumps, two elastically opposing ends form a ratchet type latch, allowing the clamp to be closed and adjusted. The top portion of the ratchet type latch having a substantially straight front edge, the front edge is undercut forming an acute angle or knife edge. The front edge configured to engage a series of transverse slots arranged vertically on the inside face of the bottom portion of the clamp. The clamp is adjusted by forcing the top portion into the bottom portion, allowing the front edge of the top portion to engage a correspondingly lower transverse slot; as the top portion is depressed, the internal cleats crimp the flexible hose closed.
One issue with the Halkey-Roberts clamp is the lack of secure engagement when a side pressure is applied or if the clamp is misaligned when closing. The Halkey-Roberts clamp has no provision to prevent lateral movement or twisting of the latch. When the clamp is closed in a misaligned or twisted configuration there are at least two issues that arise. First, the clamp cleats do not close evenly, possibly resulting in uneven metering or not fully clamping a hose closed if the user desires to completely terminate flow. The second issue is the clamp may unintentionally release. When the front edge of the top portion is misaligned with the reciprocal transverse slot, only a corner of the front edge is engaging the slot, if the clamp is bumped or jarred, the clamp can completely release resulting in unrestricted fluid flow through the flexible tubing. In the case of drug metering, a clamp release could have catastrophic results.
Other clamps have attempted to remedy this situation with varying results, including, the clamp described in U.S. Pat. No. 6,644,618 to Balbo, filed Jun. 8, 2000 (hereinafter, the Balbo patent). The device of the Balbo patent includes a vertical rib protruding from the face of the top engagement portion and a corresponding slot integrated into the vertical face of the bottom engagement portion, when the clamp is closed at least a portion of the vertical rib is constrained in at least a portion of the corresponding slot. This arrangement significantly reduces the chance that a closed clamp can be forced into a misaligned position, however, it does not appear to prevent a user from closing a clamp unevenly, or under a torsional load, and at least partially closing the clamp with the vertical rib outside of the vertical slot. Additionally, the device of the Balbo patent with the engagement of the vertical rib and corresponding slot appears to introduce a possible “pinch point” that may cause injury to the user.
What is needed is a medical clamp that fully eliminates the possibility of misaligned engagement and is easy and safe to use.